If $x \diamond y = x(y-8)$ and $x \bigtriangleup y = 3y+2$, find $-6 \diamond (2 \bigtriangleup 2)$.
Solution: First, find $2 \bigtriangleup 2$ $ 2 \bigtriangleup 2 = (3)(2)+2$ $ \hphantom{2 \bigtriangleup 2} = 8$ Now, find $-6 \diamond 8$ $ -6 \diamond 8 = -6(8-8)$ $ \hphantom{-6 \diamond 8} = 0$.